Wiring Gremlin

[geeskeet]

Okay fellas this is a weird one

I finally got my basket case chopper up and running with the Boyer ignition (also a new stator plate from JRC Engineering) and last night I started the process of cleaning up the wiring to button it up. The only things I touched was the ground wires for the battery, taillight, and reg/rec. All of which were on the same ground point when the bike ran before, all I did was attach them to the same ring and shorten the connections. The headlight I didn't even touch the wiring just relocated it a bit. Now I keep blowing the main 20a fuse.

I've checked all of those listed above for proper ground, and the headlight for good readings and they all check out. I thought maybe the fuse holder went so I checked that and it's fine as well. Now I'm stumped. I didn't mess with much and this bike has about 10 wires total so there isn't much to mess up. Not sure where to look now, the fuse blows immediately every time. Like I said, the bike ran perfectly fine before this and I didn't touch much. Any ideas on something that may have gone bad on its own?

The bike in total only has a headlight, tail light, reg/rec, battery, and a BB ignition.

 

[650Skull]

Could b a cut wire, where it goes into the headlight, shorting out.

Continuity/resistance test with your mutimeter all circuits. Save a lot of smoke from escaping.

 

[Jan_P]

Can try to disconnect things and test - If you cannot measure resistance to ground
I believe one can replace the fuse with a lamp when testing also.

 

[geeskeet]

I was just thinking about this option. There’s only a few things on the other side of the switch so it would easy enough to go through one by one and see what blows the fuse.

I’ll report back with my findings

 

[geeskeet]

I’ve dwindled it down to the reg/rec. headlight and tail light or the power box from the BB did not blow the fuse but the connection to the reg/rec blew the fuse.

Anyway to test it to confirm?

 

[650Skull]

Read up on this if your going to replace the Regulator.
https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/

 

[Jan_P]

There are inspection Routines but not simple to do a bit Difficult You'll find them in Service Manuals On line
We don't know Year model or if it is the Stock - Charging setup Especially if the alternator is stock or not -- It can short out
Downstream of a Good regulator.
Pictures perhaps or do the Readup on how to Check rotor resistance.
If it is the stock pre 1980 charging regulator and rectifier I would replace them ASAP especially with Boyer Ignition Installed
as per # 6 above

 

[geeskeet]

There are inspection Routines but not simple to do a bit Difficult You'll find them in Service Manuals On line
We don't know Year model or if it is the Stock - Charging setup Especially if the alternator is stock or not -- It can short out
Downstream of a Good regulator.
Pictures perhaps or do the Readup on how to Check rotor resistance.
If it is the stock pre 1980 charging regulator and rectifier I would replace them ASAP especially with Boyer Ignition Installed
as per # 6 above

Last night I did a little more trouble shooting and the fuse only blows when the stator/rotor is plugged in to the harness. Leading me to believe the reg/rec is still good.

I can’t be sure on my engines year, but it’s got the one piece reg/rec with the stock alternator I believe. I’ll check the engine and get some pictures for you all tonight.

 

[Its been a long time]

Last night I did a little more trouble shooting and the fuse only blows when the stator/rotor is plugged in to the harness. Leading me to believe the reg/rec is still good.

I can’t be sure on my engines year, but it’s got the one piece reg/rec with the stock alternator I believe. I’ll check the engine and get some pictures for you all tonight.

Could be one phase shorted to ground or similar. Check the alternator out as per procedure in the shop manual and described here.

 

[geeskeet]

Just to update the thread

I went ahead and tested the rings on the rotor, getting 2.5 ohms. So that failed. The reg/rec diodes tested good. I haven’t tested the continuity on the stator harness yet though.

I’m still getting the main fuse blowing when the stator harness is plugged in too, would a 2.5 ohm reading on the rotor be a symptom of a dead short? I only mention a dead short because my fuse blows immediately.

On another note, there’s these fine metal flakes laying in the stator frame that weren’t there before I got the bike started. So clearly something is rubbing on something it shouldn’t be, any ideas about that? I can’t seem to tell where it is coming from.

 

[Jim]

The rotor's supposed to be about 5Ω... so you're about half that. The current draw at that resistance is about 5amps... which is about double what it should pull. That alone wouldn't pop your fuse, but it is contributing. Put a pic up here of the rotor just to confirm, but if it's an early style rotor, I have a fresh rewind ready to go. Have a look here.

https://www.xs650.com/threads/rewound-alternator-rotor.54276/post-830339

As far as the metal flakes in the stator, there's 2 possible reasons that come to mind.
One... The stator is installed incorrectly. There's an alignment pin on the engine case that the stator slots into. It's easily overlooked if you've never installed it before, but you'll definitely get some rubbing if it's not slotted correctly.
Two... the crank is bent causing the rotor to wobble. That's much less common, but it is a possibility.

 

[Jan_P]

2.5 Ohm is perhaps Cold Without Vibrations ... ? Making it worse Once under load

 

[geeskeet]

The rotor's supposed to be about 5Ω... so you're about half that. The current draw at that resistance is about 5amps... which is about double what it should pull. That alone wouldn't pop your fuse, but it is contributing. Put a pic up here of the rotor just to confirm, but if it's an early style rotor, I have a fresh rewind ready to go. Have a look here.

https://www.xs650.com/threads/rewound-alternator-rotor.54276/post-830339

As far as the metal flakes in the stator, there's 2 possible reasons that come to mind.
One... The stator is installed incorrectly. There's an alignment pin on the engine case that the stator slots into. It's easily overlooked if you've never installed it before, but you'll definitely get some rubbing if it's not slotted correctly.
Two... the crank is bent causing the rotor to wobble. That's much less common, but it is a possibility.

Best picture of my rotor I could get at the moment just got into the garage and haven’t taken anything apart.

You can faintly see where the brush is riding on the outer ring. Whole front of the rotor has that black coating on it. I’ll get into it and see if I can’t figure out the culprit of the metal shavings.